Conservation Corner

By Andrew Stottlemyer

Are you a forest landowner who may be considering a timber sale on your property? If so, there are many variables to consider when making this decision. Carefully considering some of these variables will greatly influence the overall health of your forest ecosystem. One thing that you will want to consider would be the most desirable end results that you would like to see post-harvest. Are you looking for a woodlot that benefits wildlife? Is your main goal to remove dead and dying trees? Or are you considering a clear cut in order to make grazing land for livestock? How you see your property 5 years, 15 years, and even 30 years after the harvest will determine the type of harvest on your property. Something else to consider is whether or not you will have a professional forester involved with the harvest. A forester would serve as your ‘consultant’ and would have a moral obligation to look beyond the present-day conditions of your forest when determining the management strategy and type of harvest. If they do not and only consider financial gains for your forest, then please select someone else.

There are three basic phases in silvicultural systems that have the objective of producing a sustained yield of timber over the longterm. They are regenerating, tending and harvesting. In this system, harvesting is not the end of forest management, but simply the treatment that sets the stand back to the regeneration phase. With this in mind, the type of tree regeneration that is desired by the landowner determines the most appropriate type of harvest system that is used. There are two basic types of harvest systems. And within those two harvest systems there are harvest methods that are most effective in achieving the most desired end product for the forest ecosystem.

Even-aged harvest: Most trees are removed so that regeneration is about the same age (i.e., one age class).

Uneven-aged harvest: Single trees or small- to moderately-large groups of trees are removed; this creates two or more age classes (i.e., residual trees that weren’t harvested are one age class and regeneration that filled in the gaps created by cut trees are another age class).

Within the two basic harvest systems there are different treatments that are selected based on the tree species desired as regeneration as well as how the trees will come into the stand (i.e., seeds, stump sprouts, root suckers)

Even-aged regeneration treatments

(1) Clearcut method – removes all overstory trees in one cut; regeneration may come from seed that dropped from mature trees before they were cut, seedlings that were already present (this is called advance regeneration because it was present in advance of the harvest), stump sprouts, or root suckers. Sufficient natural regeneration may not result if there is a lack of advanced regeneration or few seeds of desirable species on the forest floor. Also, the ability of trees to sprout from the stump (once cut) decreases as diameter increases.

(2) Seedtree method – removes most overstory trees in one cut, with a few widely spaced trees left as seed sources for regeneration. Leave trees are of desirable species, form and vigor. Seedtrees may be harvested once sufficient regeneration is present, but the process of harvesting them may damage regeneration. Also, the cost of re-entering the stand for a few remaining trees may outweigh the benefit.

(3) Shelterwood method – removes overstory trees in two or more successive cuttings. In a three-stage shelterwood, a preparatory cut removes some trees to increase the vigor of the others that are to be seed sources for regeneration. Once adequate regeneration is present, a seed cutting removes more of the overstory trees to increase the light for the regeneration. Once the regeneration is well- established, remaining trees are harvested in the final removal cut. In all phases of shelterwood, merchantable trees are being harvested, particularly during the seed cutting and final removal cut.

If the stand is not quite ready to be harvested or does not yet contain adequate regeneration, there are intermediate and improvement treatments that can be performed to shape the composition of the stand.

Intermediate and improvement treatments

(1) Croptree release – pole-sized trees of desirable species, form, and vigor are selected (about 50 per acre works well) and all other trees that have crowns that touch that of a given croptree are removed by cutting or killed by herbicide injection and left standing. Trees cut during croptree release are often unmarketable or if so, only as firewood.

(2) Liberation cutting - often conducted to try to reverse the negative effects of high-grading. One of the big problems with high-grading is that the medium- sized trees that are left are low-vigor and have little potential to grow into nice timber trees, or you don’t want those trees seeding in more trees like them. Liberation cutting removes the poorlyformed, low-vigor trees that remain after a high-grade to favor seedlings and saplings that are present.

Since mentioned above, landowners should know what high-grading is, why it’s bad, and how it’s usually conducted. High-grading deliberately removes the best and often the largest trees while leaving poorly-formed, lowvigor trees standing. The problem is that the remaining trees have often been suppressed to a point where they have very little potential to become nice timber trees. Also, these trees might seed in more trees having similar characteristics and/or may shade seedlings and saplings that do have potential to grow into nice timber trees. High-grading is one of the most damaging, hard-to-correct actions that can be done to a forest. For this reason, clearcutting, although not aesthetic in many peoples’ opinion, is a much better choice of treatments; at least the most vigorous tree regeneration has the best chance of becoming the dominant trees in the stand. Diameter limit cutting (sometimes called “selective cutting” or “select cut”) removes trees above a prescribed diameter and leaves everything else and is a form of high-grading.

(3) Improvement cuttingperformed during the polestage by removing dead, dying, diseased, defective or otherwise undesirable trees to favor more desirable trees. Undesirable/invasive shrubs and grapevines can also be removed that will improve the overall quality of the timber trees. An important caveat is that the trees that would be removed in an improvement cut may have significant wildlife value as den trees, so it’s probably a good idea to leave a few. Also, the shrubs (as long as they’re not invasive) and the grapevines may be providing cover and/or food for wildlife, which might be a secondary objective of the landowner.

Interesting facts:

Seventy-one percent of Pennsylvania’s forestlands are privately owned and approximately 60 percent of Fulton County is forested.

Wood and lumber both contribute to a $16 billion industry in Pennsylvania.

Pennsylvania is the number one producer of hardwood lumber in the United States.

Also contributing to this article: Dr. Aaron D. Stottlemyer, assistant professor of forestry at Penn State University